John Audette was kind enough to send me a pair of the Osram Nightbreaker LED H4 bulbs to test last year. Its is one of the two H4 LED replacement bulbs approved in Germany mentioned above. Initially compared to the halogen 80/100 bulbs I had, I didn't think the LED replacements blew me away, and in many respects, I preferred the 3000k color over the 6000k of the LEDs, and the light output pattern of the LEDs weren't as broad and even as the halogens.

The bulb are all black powdercoated aluminum units, however I concluded after studying the shape, that if all the black surfaces that were shielding the led elements could be polished, a lot of the lost light output could be recaptured and reflected back to the upper half of the headlight reflector, increasing light output to the road, and not the sky. Looking at the pictures below, anywhere you see reflections of the LED elements in the polished surfaces are additional points of radiating light output, instead of being lost and absorbed by black paint. The result was I think a 50-100% increase in forward focus light output, and the flood of light to the sides of the focus doubled in width and light output. It now looks like the light output of modern cars, with no additional stray light above horizontal. I almost suspect that Osram engineers originally designed the housing to do this, but later painted them black to decrease the light output to meet German approval as a 55w H4 substitute.

So if you want to try LEDs for your Bosch H4 housings, I'd consider the German approved Osram Nightbreaker LEDs. Alone as is full black is similar to running 55w halogens, but if you modify and polish them as below, the light output and pattern improves significantly.

http://forums.pelicanparts.com/uploa...1727932903.JPG
http://forums.pelicanparts.com/uploa...1727932903.JPG
http://forums.pelicanparts.com/uploa...1727932903.JPG
http://forums.pelicanparts.com/uploa...1727932903.JPG
http://forums.pelicanparts.com/uploa...1727932903.JPG
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http://forums.pelicanparts.com/uploa...1727932903.JPG

Has anyone tried the LED H4 from Porsche?
https://www.porsche.com/international/accessoriesandservice/classic/producthighlights/LED-approval-documents/

Get the Philips Ultinon Pro6000 LEDs. Those are in fact what Porsche is re-branding and up-selling.

I have had them installed and they are good. Unfortunately it was immediately visible to the police and they pulled me over to check my car because of that. My car is otherwise heavily modified and it took forever for them to check everything and finally let me go. After that encounter I did switch back to the H4. But probably nothing you have to worry about on your side of the pond...